1. Field of the Invention
Embodiments of the present invention relate to a device and a method for non-destructive ultrasound testing with an improved, in particular more bubble-free, feed of a coupling medium into a coupling chamber between an ultrasound test probe and a test object to be examined in a non-destructive manner by means of ultrasound.
2. Description of the Prior Art
The principle of ultrasound inspection is known. It serves for finding casting defects or other material faults such as cracks, pockets, piping or the like. The purpose of inspecting bar material is, in particular, the inspection of internal defects and the examination for surface defects, but also the inspection of the dimensions. In this case, the ultrasonic test probe comprises at least one transmitter that is excitable by electrical pulses for generating short ultrasonic pulses that are directed into the material to be inspected of the test object. Any defect in the material to be inspected, for example a crack, a pocket or the like, causes an echo of the pulse concerned, which is reflected back to the probe and is received by the transmitter, which in this case simultaneously serves as a receiver; or the reflected echo can also be received by a separate receiver of the test probe that is disposed adjacent to the transmitter. Measuring the delay in time between the original pulse and the return of the echo permits conclusions to be made with regard to the depth of the defect. The echo strength permits displaying the size of the defect, to mention just this possibility for evaluation as an example. Furthermore, defect determination with spatial resolution is also possible.
A coupling medium is provided for the effective introduction of the emitted ultrasound into the test object. For example, a water area is provided and maintained between the ultrasound test probe and the test object to be inspected, for example the rod. For this purpose, several techniques are known, such as inspection using the immersion technique, the puddle technique or with a guided water jet. Furthermore, sealed water chambers with a test object passage often referred to as SPS also exist. After the test object has entered the sealed water chamber, the test object seals the chamber inlet and outlet. The water chamber is filled with water in order to obtain the coupling between the test probe and the test object.
Furthermore, rotary testing devices are also known. A stable water jacket is generated by rotating the entire inspecting chamber including the test probes. Disposing sealing systems at the inlet and the outlet results in a substantially tubular water jacket through which the test objects can be conveyed.
One difficulty of the known testing systems of this type is that inhomogeneities of the coupling medium, for example, of the water, affect sound propagation which may lead to misinterpretations. In particular, air bubbles in the coupling medium interfere with the inspection.
Therefore, a bubble-free coupling medium is required for ultrasound inspection. This is difficult to ensure, particularly where complex testing systems are concerned that consist of several test probes and test probe holders, and in particular if they are to be switched on or off at different times.
It is particularly difficult to ensure the freedom from bubbles of the coupling medium in such testing systems in which the coupling medium travels over long distances between the water feed and the test probes. The air-bubble-free coupling medium supply is rendered more difficult by the different cross sections and pressure conditions within the supply system, which are unavoidable due to the design requirements, however, because a transition from a rigid pipe to a movable tube, for example, is inevitable.
In the prior art, the freedom from bubbles is accomplished by flow conditions that are as continuous as possible at low flow towards the test flow, by means of large engineering efforts such as regulating valves, bypasses, quick air vents and settling tanks integrated into the supply line. In order to ensure this continuity, even in the case of changing operating conditions, great efforts also have to be made with regard to control engineering; for example, pumps are provided that are controllable by means of frequency converters.
Therefore, embodiment of the present invention provide ultrasound inspection of a test object that is more reliable with regard to diagnosis and simpler with regard to the engineering effort, in particular, of being able to supply a more bubble-free coupling medium.